CarpetLib: Introduce vect<T,D>::index

Introduce a new function vect<T,D>::index(lsh,ind), which calculates the
linear grid point index given the array size and an index triplet.

1 files changed, 14 insertions, 0 deletions

diff --git a/Carpet/CarpetLib/src/vect.hh b/Carpet/CarpetLib/src/vect.hh
index e3f6b086b..3c4232525 100644
--- a/Carpet/CarpetLib/src/vect.hh
+++ b/Carpet/CarpetLib/src/vect.hh
@@ -434,6 +434,20 @@ inline int minloc (const vect<T,D>& a) {
   return r;
 }
 
+/** Return the n-dimensional linear array index.  */
+template<typename T,int D>
+inline T index (const vect<T,D>& lsh, const vect<T,D>& ind) PURE;
+template<typename T,int D>
+inline T index (const vect<T,D>& lsh, const vect<T,D>& ind) {
+  T r(0);
+  for (int d=D-1; d>=0; --d) {
+    assert (lsh[d]>=0);
+    assert (ind[d]>=0 and ind[d]<lsh[d]);
+    r = r * lsh[d] + ind[d];
+  }
+  return r;
+}
+
 
 
 // Higher order functions